Secondly, have you checked to see if the act.service.host file is running on the service list?

Thirdly, is Universal Search working within the Windows client?

These last two are related, but worth tested individually in that order. If the service is stopped, your issue will be fixed with a simple restart of the service.

If your database and publishing application are on different server's, then you will likely have to edit your act.service.host config file to point the search command from the local host to the IP of the database server.

Given the problem started after a recent update, I'm inclined to think #1 is not related.